import React, { Component } from 'react'
//引入store，用于获取redux中保存的状态
import store from '../store'

export default class Count extends Component {
  componentDidMount() {
    //检测redux中状态数据的变化，只要变化，就调用render
    store.subscribe(() => {
        this.setState({})
    })
  }

  increment = () => {
    const {value} = this.selectNum;
    store.dispatch({type: 'increment', data: value*1})
  }
  decrement = () => {
    const {value} = this.selectNum;
    store.dispatch({type: 'decrement', data: value*1})
  }
  //奇数再加
  incrementIfodd = () => {
    const {value} = this.selectNum;
    const count = store.getState();
    if(count % 2 !== 0) {
        store.dispatch({type: 'increment', data: value*1})
    }
  }
  //异步加
  incrementAsync = () => {
    const {value} = this.selectNum;
    setTimeout(() => {
        store.dispatch({type: 'increment', data: value*1})
    }, 500)
  }
  
  render() {
    return (
      <div>
        <h1>当前求和为：{store.getState()}</h1>
        <select ref={c => this.selectNum = c}>
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
        </select>&nbsp;
        <button onClick={this.increment}>+</button>&nbsp;
        <button onClick={this.decrement}>-</button>&nbsp;
        <button onClick={this.incrementIfodd}>当前求和为奇数再加</button>&nbsp;
        <button onClick={this.incrementAsync}>异步加</button>&nbsp;
      </div>
    )
  }
}
